Immune system discovery likened to finding a new continent

In this image of the immune system attacking a virus, the Y-shaped stalks on the cells below are the epitopes(Credit: Ugreen/Depositphotos)

Thanks to the hard work of explorers and cartographers through the centuries, we've now identified all of our planet's landmasses. But when it comes to the landscape inside the human body new findings still await, and finding them can bring the same thrill that the discovery of a new continent once brought to adventurers. That's how one researcher describes work that's been done in identifying the way cells send up flags to the body's immune system – a discovery that could have a significant impact on how we develop vaccines or treat autoimmune diseases.

In a new study published today in the journal Science, researchers detail work they've done with epitopes. These protein fragments are sent out to the surface of cells for scanning by our bodies' immune systems. When an epitope registers as foreign to the immune system, it goes to work destroying the cell displaying it.

But sometimes the signaling can get complicated when the cell splices two protein bits together and sends them to its surface. Such spliced epitopes have been known about by scientists, but their existence was thought to be rare. The new study shows that about 25 percent of all epitopes are spliced.

This is significant because, while a spliced epitope can let the immune system know that disease is present, it can also confuse the immune system into thinking a healthy signal is actual harmful. And that could be what leads the body to turn on itself in autoimmune diseases such as multiple sclerosis.

"It's as if a geographer would tell you they had discovered a new continent, or an astronomer would say they had found a new planet in the solar system," said study co-author Michael Stumpf from the Department of Life Sciences at Imperial College London. "And just as with those discoveries, we have a lot of exploring to do. This could lead to not only a deeper understanding of how the immune system operates, but also suggests new avenues for therapies and drug and vaccine development."

But the researchers also say that the work comes with a catch.

"The discovery of the importance of spliced peptides could present pros and cons when researching the immune system," said lead author, Juliane Liepe, also from Imperial's Department of Life Sciences. "For example, the discovery could influence new immunotherapies and vaccines by providing new target epitopes for boosting the immune system, but it also means we need to screen for many more epitopes when designing personalised medicine approaches."

In other words, be careful what you wish for.

Liepe led the research with Dr. Michele Mishto from Charité - Universitätsmedizin Berlin in collaboration with the LaJolla Institute for Allergy and Immunology and Utrecht University.